Epigenetic switches: can infidelity govern fate in microbes?

Unicellular organisms are constantly subject to sudden changes in environment. Here, we describe recent progress in understanding how epigenetic mechanisms can generate differentiation within genetically identical single cells of a clonal population. Such intrinsic phenotypic heterogeneity within a population may be considered as a bet-hedging strategy in fluctuating environments. One aspect we highlight is how transient errors in information transfer, be it errors in transcription or translation, or alternatives in protein folding, can influence the quantity and the quality of the resulting proteins, and therefore, contribute to genetic noise within individual cells. These stochastic events can provide the impetus for heritable phenotypic change in bistable epigenetic regulatory networks that are susceptible to noise and proteins capable of dominant variant conformations.